Fabrication of quantum devices by Ångström-level manipulation of nanoparticles with an atomic force microscope

We describe a technique for the fabrication of lateral nanometer-scale devices, in which individual metallic nanoparticles are imaged, selected and manipulated into a gap between two electrical leads with the tip of an atomic force microscope. In situ, real-time monitoring of the device characteristics is used to control the positions of the particles down to atomic accuracy and to tune the electrical properties of the device during fabrication. Using this technique we demonstrate a nanomechanical switch as well as atomic-scale contacts that are stable at quantized conductance levels on the time scale of hours at room temperature.